Add authentication to the current Convex + web app — passkeys by default (OAuth/password optional), wired end to end incl. the auth.config.ts that's the #1 auth footgun. TRIGGER when the user wants login / sign-in / accounts / passkeys / OAuth for an existing app.
$npx -y skills add get-convex/convex-backend-skill --skill authInstalls into the current project.
Run `npx skills use "https://github.com/get-convex/convex-backend-skill" --skill "get-convex/convex-backend-skill/auth"` and follow the generated skill instructions now. Read its complete output, redirecting it to a temporary file first if necessary. Resolve relative paths from the supporting-files directory it provides.
Use the skills in "https://github.com/get-convex/convex-backend-skill" that are relevant to the current task. Run `npx skills add "https://github.com/get-convex/convex-backend-skill"` and select the relevant skills, then follow their instructions.